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The Core Difference Between Reflex and Low Latency Mode
Both NVIDIA Reflex and Ultra Low Latency Mode share the same ultimate goal: reducing overall system latency and input lag. While they both use similar strategies to achieve this, their methods of implementation differ significantly.
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How does NVIDIA Reflex Work?
Unlike driver-level settings, NVIDIA Reflex must be integrated directly into a game by the developers. Because of this, you won't find a "magic" driver-level version that works for every title; it is primarily found in competitive shooters, though it is appearing in more modern titles every day. In your in-game settings, you will typically see options labeled Off, On, and On + Boost.
When you enable NVIDIA Reflex, it forces your CPU and GPU to work in perfect sync, effectively eliminating the traditional render queue. Instead of the CPU queuing up completed frames for the GPU, it essentially zeroes out the queue. The process works in a tight loop: the CPU hands the latest frame data (containing inputs from your mouse and keyboard, as well as current physics) directly to the game engine. The engine then checks if the GPU is ready; if it is, the frame is processed immediately.
By ensuring the CPU only sends the most current data rather than a backlog of queued frames, the system dramatically lowers both in-game and input latency. Depending on your specific PC hardware, this can typically cut input lag by 10–40 milliseconds or reduce overall system latency by anywhere from 20% to 75%.
How does NVIDIA Ultra Low Latency Mode Work?
NVIDIA Ultra Low Latency Mode (ULLM) is actually quite similar to NVIDIA Reflex, but it operates purely at the driver level. It also works to eliminate the frame queue, delivering frames to the GPU "just-in-time," as many others have described it.
The biggest difference comes down to performance and how much deeper the in-game coded Reflex can actually go. Because ULLM doesn't talk to the game engine directly, there is no direct communication between the driver and the game. Instead, the driver basically has to play a guessing game of exactly when to send the next frame to the GPU. Because it's a driver-level guess, the timing can miss out on sync up with your exact, real-time peripheral inputs and the current in-game physics.
When to Use NVIDIA Reflex (In-Game Settings)
As a rule of thumb, we say you should almost always enable NVIDIA Reflex in-game, provided it doesn't cause unexpected stutters or lower your average frame rates in demanding AAA titles. However, it is important to understand the difference between On and On + Boost, as each setting handles system performance slightly differently.
NVIDIA Reflex On vs. On + Boost: Which Do You Use?
Reflex Low Latency "On": This setting forces your CPU and GPU to work in sync, effectively eliminating the traditional render queue while keeping your GPU power-saving features active. You should use Reflex On when you are GPU-bottlenecked in-game, if you see your GPU usage close to the 99% mark, turn it on. This is most commonly used with high graphic settings, usually in non-competitive games.
Reflex Low Latency On + Boost: This option delivers the exact same latency reducing queue synchronization as the standard "On" mode, but overrides your GPU's power saving states to keep the graphics card running at its maximum frequency. It tends to drop latency a little bit more and is commonly used in competitive FPS games. This setting is highly recommended when your game is CPU intensive, hitting high CPU usage but your GPU sits under 80% usage or less in-game. It forces the GPU to stay awake and ready to render instantly.
Should You Enable Ultra Low Latency Mode (Control Panel)
Generally, we don't really see the point in turning it on most of the time. The most important games that need lower latency already take advantage of NVIDIA Reflex these days, which, more often than not, means competitive games. You'll also see it in AAA titles that have NVIDIA Frame Generation, where NVIDIA Reflex is turned on automatically.
When do you turn on Ultra Low Latency Mode?
We recommend enabling this feature for specific games rather than in your global settings. Depending on the game and your hardware, there is a likely chance of stutters and bad frame pacing if it's left on globally.
However, the plus side is that in older competitive titles, you can take advantage of lower latency without worrying about whether the game implements Reflex or not. Additionally, if you use apps like Lossless Scaling on Steam, you can use Ultra Low Latency Mode in combination with frame generation on any game. Overall though, you're likely not going to play a story game and worry about latency at 60 to 120 FPS, you'll just be too busy enjoying the graphics and story the world offers.
Can You Use NVIDIA Reflex and Ultra Low Latency Mode At The Same Time?
The short answer is no. When you turn on NVIDIA Reflex while Ultra Low Latency Mode is enabled, Ultra Low Latency Mode will automatically be ignored and Reflex will take over as the active setting.
However, I suppose in a way, that means you can leave Ultra Low Latency Mode on globally if you absolutely wanted to. By doing that, you wouldn't have to worry about manually enabling it for older titles, and whenever Reflex is available in a modern game, you can just turn it on to automatically override ULLM.